Different Types of Autism

Autism is often referred to as a spectrum disorder, meaning that the symptoms and characteristics of autism can present themselves in a wide variety of combinations, from mild to severe. Although autism is defined by a certain set of behaviors, children and adults can exhibit any combination of these behaviors with any degree of severity. Two children with a diagnosis of autism can act very differently from one another.

A diagnosis of autism is based on the standards set forth in a diagnostic handbook, the Diagnostic and Statistical Manual, now in its fourth edition (DSM-IV -TR-2000). Several autism-related disorders are grouped under the broad heading “Pervasive Developmental Disorder” or PDD. They include autism, PDD-NOS (pervasive developmental disorder, not otherwise specified) and Asperger’s disorder. These diagnoses are often used differently by professionals to describe individuals who manifest some, but not all, of the characteristics associated with autism.

The diagnosis of autism is made when a specified number of characteristics listed in the DSM-IV are present in ranges inappropriate for the child’s age. By comparison, a diagnosis of PDD-NOS may be made when a child exhibits fewer symptoms than in autism, although those symptoms may be exactly the same as those in a child with an autism diagnosis. Asperger’s disorder tends to involve symptoms more markedly different than those seen in autism, although there are some similarities.

Each diagnosis relies on perceptive observations of the child, ideally across several settings (home, school, clinic, etc.), by professionals with a knowledge of autism. Some professionals believe the distinction between autism and PDD-NOS is not significant. Some may believe they are “sparing” the parents by giving a diagnosis of PDD-NOS rather than autism. Many professionals still argue whether Asperger’s is truly a form of autism. It’s important to understand that whatever the type of autism diagnosis, these children are likely to benefit from similar approaches to education and treatment.